Trimming mechanism for sewing-machines.



J. R. MOFFATT.

THIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JUNE 5,1915.

1,232,365. Pateflted July 3, 1917.

2 SHEETS-SHEET I- J. R. MOFFA'IT.

TBIMMING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JUNE 5. I915- I 1,232,3 5, v Patented July 3,1917.

2 SHEETSSHEET 2.

UNITED STATES PATENT oFFIoE.

JAMES 3. Manama, or cnrcaeo, ILLmoIs, assIeNoIt TO UNION SPECIAL MACHINE COMPANY, or CHICAGO, ILLINOIS, A CORPORATION or ILLmoIs.

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I Specification of Letters Patent.

To all whom it may concern: Be it known that I, JAMES R. Morm'r'r, a citizen ofthe United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certalnnew and useful Improvements in Trimm ng Mechamsm for Sewing-Machines, of which the following is a description reference being had to the accompanying drawing and to the figures of reference marked thereon.

Theinvention relates to new and useful improvements in trimming mechanisms for sewing machines and more partlcularly 'to improvements in' the lower or stationary trimming blade of an overedge machine such as shown in the patent to Onderdonk, 1,048,204, granted December 24th, 1912.

An object of the invention is to provide a lower trimming blade whichwill give a bearing surface for the tail of the upper trimming blade throughout theentire movement of said upper blade, which trimming blade can be attached to a machine without making any changes in the position of the stitch forming elements. I

A further object of the invention is to provide a stationary blade which may be located beneath the work support and which is so shaped and disposed that said blade may be made considerably longer than heretofore when an inclined straight blade has been used.

These and other objects will in part be obvious and will in part be hereinafter more fully disclosed.

In the drawings which show. by way of 'illustration one embodiment of the invention: I I

Figure 1 is a front view showing a sewing machine having my improved trimmer blade applied thereto;

Fig. 2 is a transverse vertical sectional view showing'the trimming mechamsm in side elevation;

Fig. 3 is a top plan view; and

Fig. 4 is a detail showing the two trimming blades in side elevation and in a different position from that shown in Fig. 2;

Fig. 5 is a sectional view through the support for the lower trimming blade, showing the manner of clamping the said blade.

I have shown my invention as applied to a sewing machine consisting of a supporting bed 1 having a standard 2 carrying an overhanging arm 3 in which reciprocates .the ne dle bar 4 carrying a needles). The

needle bar 4 is recipr ca-te'd by an oscillating needle lever Gwhich is actuated by an eccentric rod 7 from an eccentric on the main shaft 8. Cooperating with the needle beneath the work support is a looper 4 WhiCl1 '.iS mounted on a looper carrier 10 pivoted to a bracket 11.

Patented July 3, v1917. l

The looper currier is oscillated by a link 12 which is connected to a rock shaft 13 and said rock shaft is connected through a link 14 to the needle lever extension 15. I

The material is supported on a work support 16 and is held thereon by a presser foot 17 carried by a presser bar 18. The above type of machine is especially designed for forming an over edge stitch.

The trimming mechanism operates upon thefabric in advance of the stitching mechanism and consists of a movable trimming blade 19 which isclamped to an arm 20 which may be connected to an arm 21 pivoted at 22. This arm" 21 is connected to an eccentric strap 23 which cooperates with an eccentric 24 on the main shaft 8. Locatedbeneath the work support is the stationarytrimming blade 25 with which the movable trimming blade 19 coiiperates- The curved on the arc of a circle as clearly shown in Figs. 2 and 4. Said blade is supported by a bracket 28 and is so disposed that the blade curves outwardlyaway from a vertical line.

passing through the trimming point, that is, outwardly away from the machine or toward the operator. By this construction of the blade I am able to make a very muchlonger blade than has heretofore been used where the blade has been'straight and inclined.

Located beneath the trimming blade is a part of the looper mechanism as shown in Fig. 2 and this makes it essential that the blade should extend outwardly from the vertical line passing through the trimming point so as to give a proper clearance for these operating parts beneath the same. By curving the blade as above described, I am able to make a much longer blade, one that extends well out fromin front of the depending skirt 29 of the work support 16.

The bracket 28 which supports the curved blade has a recess 30 for'the blade and said recess is tapered so as to engage the tapered edge of the blade to hold the same seated therein.

A clamping plate 31 secured by a screw 32 clamps the blade in place.

It will-be noted from the drawings that this lowerstationary blade is of the same cross sectional area throughout its length so that as said blade is ground away for sharpening the same, a uniform cutting surface is provided. The movable blade 19 moves from the position shown in Fig. 2 to ,the position shown in Fig. 4. The guiding toe 26 of the blade makes continual contact throughout the entire overlap of the toe with blade located in front of the trimming point and this positions the blade, as above described. By this shaping of the stationary blade, the tail of the upper movable blade makes continuous contact with said lower stationary blade throughout its entire movement. If the guiding tail in its downward movement moves at any portion thereof off from the lower blade, it is apt to wear a-channel therein. Where, however, the tail of the movable blade continuously bears the lower onary blade at extreme end, the objection aboye noted is l 2. A trimming machine including a work support, an upper movable trimming blade having a depending guiding projection atthe rear edge thereof, and a lower stationary trimming blade beneath the work, support,

said lower bladebeing of substantially the same cross sectional area throughout and curved on the path of a circle, said blade being disposed so that the guiding projection makes a continuous contact with said lower 'blade throughout the entire part of said projection extending below the cutting edge of said lower blade.

In testimony whereof, I aflix my signature in the presence of two witnesses.

JAMES R. MOFFATT.

Witnesses; I

S. GEORGE TATE, STEDMAN THOMAS. 

